The present invention relates to skylights, and more particularly to tubular skylights, which include a reflective tube extending downwardly from the dome.
Tubular skylights have acquired increasing popularity as a means of introducing natural light into a building interior. These skylights include a dome with flashing mounted on the building roof, a light diffuser mounted in the building ceiling, and a reflective tube interconnecting the dome and the diffuser. Natural light entering the skylight through the dome reflects downwardly through the tube to the diffuser. The tube in a sense acts as a gigantic optical fiber. Typically, the domes are fabricated of clear plastic; and the tube is fabricated of aluminum with a reflective coating.
The efficiency of such skylights (i.e. the amount of natural light reaching the building interior) is primarily a function of the amount of light passing through the dome into the tube and of the reflective efficiency of the tube. It is desirable to channel or steer as much light as possible downwardly through the tube to illuminate the building interior. One such approach is seen in U.S. Pat. No. 5,655,339, issued Aug. 12, 1998, to DeBlock et al, and entitled "Tubular Skylight with Improved Dome." This approach utilizes a series of prisms along one portion of the outer surface of a hemispherical dome to reflect light downwardly into the tube. The prisms converge near the top of the hemisphere. However, in direct light the converging prisms cast shadows which can be seen on the underside of the diffuser. Additionally, although the prisms are a significant improvement in directing the light downwardly, improved efficiencies are still desired. Further, the dome is aesthetically deficient when mounted on the roof.